Vacuum or pressure operated switches have been used in the automotive industry for many years to transduce a change in pressure to an electric signal usable either to control another function or to simply provide an indication of condition to the operator. An example of the latter would be a pressure transducer for actuating a warning light on the vehicle dashboard when oil pressure falls too low.
The present vacuum operated switch, however, is specially designed for the former purpose, i.e., to control a subsequent function. In this case the switch is designed to sense engine manifold vacuum and to control a transmission converter locking mechanism. It is also designed to energize and deenergize emission control components. While designed for the requirements of these specific applications, the present switch assembly of course has other applications as well.
The basic switch mechanism is of the movable over-center contact blade type that carries a contact pivotable between two aligned stationary contacts. A spring biases the blade from its center position to provide the necessary snap action for the switch. This basic switch mechanism is combined with a diaphragm actuator to form the complete switch. This mechanism is prior art, but the prior art switches of this type all require an excessive number of parts for supporting the stationary contacts, as well as the movable contact blade, and they also require wiring between the terminal and contacts, both of which contribute significantly not only to the cost of the parts and particularly to the labor cost in assembling the device, but also negatively to the reliability of the switch itself.
It is a primary object of the present invention to ameliorate these prior art problems found in vacuum and pressure switches.